Seeds for the Future = Challenges for Potato

The quality of seed potatoes is of paramount importance. The Netherlands and France are important seed potato exporters. In France, seed potato production is a well-organised and economically important sector in which genetic crop improvement and advancement of seed health are crucial objectives. There are strong debates in France on the use of new breeding techniques, which require special skills, equipment, facilities and investments, but which are not always accepted by the general public. The seed potato sector should prepare itself for a situation in which pests and diseases will adapt themselves to global change. Moreover, pests and diseases may thrive under the reduced use of chemical crop protectants. In this regard, it is essential to assess which multiplication techniques will have a better future: are we going to grow potatoes on the basis of seed potato schemes or on the basis of true potato seed? At the same time, there are many national and international changes in legislation about seed production. The seed potato sector must prepare itself for a diverse set of changes in a very dynamic world.     

Genomics and crop response to global change: what have we learned?

Global change poses major challenges for research in fields ranging from crop improvement to water and fertilizer management. Plant genomics is often promoted as a likely source of breakthroughs in understanding plant response to temperature and water stress. This special issue includes papers that range from consideration of gene-to-phenotype associations to papers at the system scale that examine successes and problems with linking physiology and genomics for global change research. Key themes covered include “How genomics can contribute to global change research,” “Genomics and basic understanding of crop responses to the environment,” and “What can field-level physiology bring to genomic research?”. Extrapolation from the model species arabidopsis [Arabidopsis thaliana (L.) Heynh.] has proven more problematic than anticipated, but new techniques and advances in gene sequencing of crop species helps compensate for such difficulties. Physiological research complements genomics by bringing an understanding of the response of the whole plant or crop to differing environments. Physiology also leads to an appreciation of how macro-scale processes such as photosynthesis and partitioning add biological meaning to genotype-by-environment interactions that are significant statistically but otherwise are not meaningful. Furthermore, physiologists have traditionally measured phenotypes in careful detail, and they have a clear role in adding precision to research on gene-to-phenotype associations. Research on crop response to global change has much to gain from strengthened collaboration between genomics and field-level crop physiology.     

Utilization of potato genetic resources in variety development

Potato varieties of Europe, widely grown prior to the late blight epidemic of the 1840s, were apparently derived mainly from ChileanSolanum tuberosum Group (Gp) Tuberosum and with contributions from Gp Andigena. A small number of these old varieties had field resistance and consequently survived the late blight. These survivors, along with a limited number of 19^th and early 20^th century introductions, provided the very narrow genetic base for our modern potato variety development. Beginning in the first half of the 20th century, resistance to diseases and pests from exotic species and primitive relatives was backcrossed into the existing parental stocks, with little improvement in broadening of the genebase. By the 1980s, 77% of European and somewhat fewer North American varieties had genes, derived by backcrossing, fromS. demissum (late blight resistance) and Andigena (resistance to cyst nematode). Broadening of the Tuberosum genebase was undertaken in 1959 by creating long-day adapted Neo-Tuberosum (N-T) from large populations of Andigena. This took six or more cycles of recurrent mass selection. Simmonds, in England, was the first to begin this work, followed shortly after by Plaisted, in the U.S., and Tarn, in Canada. Varieties with N-T in their pedigrees include the New York releases “Rosa”, which is 50% N-T, and “Eva”, 25% N-T. The Tuberosum genebase has also been broadened with diploid Gp Phureja resulting in the releases of “Yukon Gold,”with yellow flesh and high internal quality, and “NorValley,”a chipper with resistance to cold sweetening. Over 5000 accessions of about 150 wild species are available to breeders from the U.S. Department of Agriculture, National Research Support Project 6 (NRSP-6) genebank. Many of these accessions have been evaluated for resistance to diseases and pests as well as other important traits. Six genebanks in other countries also have many accessions for breeders. These seven collections are a great source of valuable traits for breeding, but remain under-utilized, mainly because of the time and additional resources required in eliminating the “wildness”characters associated with the desired traits. “Pre-breeding”is needed to help breeders utilize the many needed genes and alleles in the wild species. There now are two projects with pre-breeding as an objective in the U.S., one at Madison, WI, and the other at Prosser, WA. Resistance to cold sweetening (low sugar build up in cold storage) has been backcrossed from several wild species into the Tuberosum background, as has resistance to late blight, the Columbia rootknot nematode, and the potato leafroll virus (PLRV). Resistance to potato virus Y (PVY) and PLRV obtained from N-T has been incorporated into Tuberosum parental stocks. Durable resistance to late blight in Polish breeding stocks, withS. demissum andS. stoloniferum background, and in improved Bolivian and Peruvian Andigena has also been utilized by North American programs.     

Introgressive Hybridization in Potato Revealed by Novel Cytogenetic and Genomic Technologies

Potato is the third most important food crop in the world and is crucial to ensure food security. However, increasing biotic and abiotic stresses jeopardize its stable production. Fortunately, breeders count on a rich pool of wild relatives that provide sources for disease resistance and tolerance to environmental stresses. To use such traits effectively, breeders require tools that facilitate exploration and exploitation of the genetic diversity of potato wild relatives. Introgression programs to incorporate such alien chromatin into the crop have so far relied on cytogenetic and genetic studies to tap desired traits from these wild resources. The available genetic and cytogenetic tools, supplemented with more recent genomic technologies, can assist in the use of potato relatives in pre-breeding. This information can also facilitate cisgenesis and genome editing to improve potato cultivars. Despite the abundant and rapidly growing genomic information of potato, that of its wild relatives is still limited.     

Advances in Modelling the Potato Crop: Sufficiency and Accuracy Considering Uses and Users, Data, and Errors

When we consider complex, multi-step processes such as crop growth or the progress of a disease then simple mathematical functions are inadequate to describe them and we generally use some kind of mathematical model. The commonest form in use is one that we call a simulation model although there are other forms of model such as Rule-based, (e.g. Gu et al. AI Appl 10:13–24, 1996), Bayesian (Gold, Plant Disease Epidemiol 4:84–122, 1989) and ‘fuzzy’ (Burrough, J Soil Sci 40:477–492, 1989), depending upon the application. Models may sometimes be combined into packages that we call decision support systems. This paper will consider simulation modelling and also the combination of complementary models. Mathematical models of the potato crop have been devised, in a range of sophistication, over a long period of years and a quite proper question is: “Where next? What are the developments that are sought or, more importantly, that are needed?”     

鲁棉一号选育与推广的细节追忆

通过对20世纪80年代在全国推广面积最大的鲁棉一号选育推广回顾,阐述了历经杂交组合配制、钴原辐射和选育推广过程的关键细节,旨在了解那一代棉花育种人艰苦探索、科研创新、团结协作、共同攻关的科研精神以及对主攻育种目标全面性和敏锐性的把握。     

QTL Analysis of Late Blight Resistance in a Diploid Potato Family of Solanum spegazzinii × S. chacoense

Several quantitative trait loci (QTL) for resistance to late blight have been reported in diploid potatoes. The diploid wild potato species Solanum chacoense possesses a high degree of horizontal resistance to late blight. In the present study, we report on QTL mapping for late blight resistance in a diploid mapping population of 126 F₁ of Solanum spegazzinii (susceptible) × S. chacoense (resistant). The area under the disease progress curve (AUDPC) values for late blight resistance using the “whole plant in vitro assay” and the “detached leaf assay” on the mapping population displayed quantitative variation. Out of 64 AFLP primer-pairs combinations and SSR markers, a total of 209 significant AFLP loci were placed onto the 12 linkage group of potato covering a total map length of 6548.1 cM. QTL analysis based on the AUDPC dataset of the “whole plant in vitro assay” using the interval-mapping option identified two QTL (LOD?>?2.5) located on linkage groups IX and X, which explained 14.70 and 3.40% variation, respectively. The present study revealed the presence of potential new genetic loci in the diploid potato family contributing to quantitative resistance against late blight.     

现代数字育种技术的研究进展

现代计算机技术促进了作物育种技术的数字化进程.随着作物性状数据采集技术的发展成熟,作物育种过程中产生的数据呈指数增长,促使传统作物育种技术变革.作物育种过程中产生的数据类型十分复杂,数据的存储、分析和利用是作物育种技术的一个组成部分,促成了现代数字育种技术的迅猛发展.通过分析玉米育种过程中涉及到的各类数据,提出概念性的作物育种数据管理系统框架,并阐明各类数据之间的相互关系.完善的育种数据管理系统除核心数据库外,还包括多项数据分析模块,包括系谱树和亲缘分析、分子标记和基因定位、数据采集和性状分解、杂交组合和后代选择、育种策略分析、田间试验设计和统计分析、生长发育系统模拟和基因功能和调控网络等.数据分析模块可以根据作物育种实践的实际需要进行组合,但并非所有模块都是必需的.     

The Contribution of Traditional Potato Breeding to Scientific Potato Improvement

Conventional potato breeding refers to development of new cultivars from sexual crosses followed by clonal propagation and selection. Nearly all new varieties of potato still emerge from this process free from modern technologies of gene insertion. Conventional breeding remains the most important force for introduction of new phenotypes underlain by new genes. However, these come from already selected potato breeding lines or named varieties or from wild potatoes or more distant solanaceous relatives that are amenable to somatic hybridization. Potato breeders are constantly searching for new germplasm, in part because the potato as a crop still remains highly vulnerable to biotic and abiotic stresses. In addition, the widening of the genetic base is seen as a means of increasing heterozygosity. Despite a highly conscious import of genetic variability, commercial varieties often emerge from a relatively restricted genetic pool. This is due to the long list of traits that must fall within narrow boundaries of performance. The potato must be able to navigate the conditions of modern agriculture, withstand unusual weather events, and arrive at harvest with skin and flesh appealing to the market for which it is intended. A storage period must also be endured during which appearance and suitability for processing or the consumer’s kitchen must be maintained. A lapse in any of these phases usually signals that a new variety will exit commercial use as fast as it entered. The inconvenient accompaniment of introducing exotic genetic variation is that the breeding products are often outside of the targeted market niche. It is not surprising that many new varieties stem from crosses from older named varieties. Efforts to diversify are in conflict with conformism leading to relatively high co-ancestry coefficients between advanced breeding lines. Conventional breeding has advanced through the last hundred years the appearance, sugar status, Verticillium resistance, and yield of larger sized tubers in statistically robust ways. Potato arrived from the new world and very quickly became the secret solution to famine for the poor by virtue of its productivity and nutrient content. Meanwhile, in modern times, challenges to the consumption of potato come from a sedentary and carbohydrate over-satiated society. The genetic repository of potato germplasm is so rich that a new era of potato varieties beneficial to health may be at hand. Conventional breeding will certainly be a major part of this.     

Norgold Russet and Norgold Russet strain M — additional evidence for genetic dissimilarity

Potato improvement through strain selection has been under-exploited and sometimes discredited by plant breeders, even though successes, such as Russet Burbank, have been recognized. For years, seedsmen have rogued out “off-types” in order to maintain varietal purity. It is suggested that these off-types can sometimes offer an opportunity for developing improved strains or, depending on definition, improved varieties similar to the original variety, but possessing one or more unique characters which render it more acceptable or better adapted than the original variety. In Texas, Norgold Russet strain M, a selection out of Norgold Russet, is such an example. In this investigation, 2 genotypes, Norgold Russet and Norgold Russet strain M, were analyzed based on yield and plant attributes from 2 Texas sites over an 11-year period. Significant genotype x site, genotype x year, and genotype x site x year interactions were found, supporting the hypothesis that these 2 potato genotypes are phenotypically and presumably genetically dissimilar. Canonical discriminant analysis, using yield and plant attributes, confirmed these findings and provides additional evidence that varietal strains might deserve designation as unique varieties.     

中国杂交水稻白叶枯病抗性的遗传改良

 20世纪80年代,中国杂交水稻抗白叶枯病育种进展迅速。在大面积种植的籼型三系和两系杂交稻中主要应用白叶枯病抗性基因Xa4,白叶枯病在生产中几乎“销声匿迹”了20年。但近年来,此病害却在长江流域一些种植新组合的稻田里又爆发了。什么原因引起它再度流行？品种的抗性是否还有效？抗病育种是否还是水稻改良的主要目标之一？通过哪些途径才能更有效地利用抗病基因培育出更为持久的抗性品种？为回答这些问题,就我国杂交水稻对白叶枯病抗性的改良,寄主与病菌群体的互动演变效应进行了分析,讨论了拓宽抗性遗传基础、白叶枯病菌毒性群体结构、基因轮换、合理利用基因等问题。 在采用了包括传统方法、分子标记辅助选择和转基因技术的综合策略后,杂交水稻抗白叶枯病育种研究将出现新的局面。     

Alaska red: A general purpose,productive, red-skinned potato

‘Alaska Red’ is the first red-skinned potato bred and selected in Alaska as a clone suitable for the fresh potato market. Its parents are Alaska Clone 11-57-1-59 and ‘Red Beauty’. It is a high yielding, medium specific gravity potato with uniform skin and eye basin color, shallow eyes, uniform oval-to-flattened shape and is very attractive. The flesh is snowy white and remains white after boiling. Alaska Red keeps well in storage at 38°F (3.3°C). Scab of the tubers is the only disease that has been observed. In this subarctic region, flowers abort in the early bud stage. Red-skinned potato varieties available to Alaskan growers for the past quarter century have been unsatisfactory due to one or more of the following characteristics: low dry matter content, poor yield, uneven skin pigmentation and internal or external tuber cracking. Although consumers buy far less red than white-skinned potatoes, the demand brings Florida “reds” to Alaska as well as “reds” from other regions so that there is a year round outlet. Imported “reds” never approach the high quality of Alaskan grown “reds”. During the screening of seedlings, ‘Red Beauty’ was selected as a parental line because of its excellent conformation, skin color and eye arrangement. Low yield and shatter cracking made it unsuitable for commercial production. Alaska Red is a selection from seedlings of the cross Ak. 11-57-1-59 and Red Beauty made in 1965 and is the first red-skinned potato released from Alaska’s potato breeding. It was first evaluated by potato growers in 1972 and released in 1976 by the Agricultural Research Service, United States Department of Agriculture, Box AE, Palmer, Alaska 99645.     

The Value of Seed Potatoes from Four Systems in Kenya

Although potatoes are the second most valuable crop in Kenya, poor seed potato quality has limited industry expansion. The objectives of this study were to describe the seed potato system, identify problems, determine use of high-quality seed and estimate farmer willingness to pay (WTP) for different types of seed. Data was collected from interviews, forums and surveys. A contingent valuation method (CVM) model was also developed to analyze the factors that influence farmer WTP. It was found that the seed system consists of three sub-components: Formal, Semi-Formal and Farmer. More than 96 % of Kenya seed potatoes were produced in the Farmer category, and were considered to be poor quality. Growers identified bacterial wilt, viral diseases and late blight as the most serious problems. The WTP model revealed that farmer age, distance to seed source, potato training, gender and region were statistically significant explanatory variables. The study recommends that training be conducted to increase production of “clean seed” and “positively-selected seed” in the Semi-Formal part of the seed system.     

Luxury Absorption of Potassium by Potato Plants

Pot and field experiments were conducted to test whether excessive potassium (K) uptake by potato plants occurs under conditions with or without irrigation at different sites. The results from both pot and field experiments showed that potato biomass and tuber yield peaked at a certain level of external K, and did not increase further with additional K supply. However, K absorption by potato plants continued to increase within the range of K used. It was concluded that luxury absorption of K by potato plants occurred with high K availability in the media. This suggests that K fertilizer recommendation based on the index “K requirement per tuber production” may be unreliable, because the optimum crop need varies with production conditions.     

The potato genetic resources held in trust by the International Potato Center (CIP) in Peru

Summary Potatoes account for about half of the world's annual output of all roots and tubers, and since the early 1960s, the increase in area planted in developing countries has been higher than for any other major food crop. Annual world production currently totals 274 million tons on 18 million hectares, with China and India accounting for 22 percent of this total. In less than a generation, most of the world's potatoes will be harvested in Asia. Africa, or Latin America, where the potato is becoming an increasingly important source of food and its cultivation provides rural employment and income for the growing population. The rapid emergence of processing facilities for the fast food industry, and the indirect influence of improved rice and wheat irrigation systems have also contributed to the expansion of potato production in Asia. The demand is strongest for processing quality potatoes that supply the fast food chains in large urban concentrations where processed potato products fetch top prices. Such increasing demand is putting strong pressure on national and international breeding institutions to produce high quality processing varieties well adapted to the wide array of agro-ecological conditions, in South East Asia in particular. The lack of adequate seed systems in this region is the single most important impediment to the expansion of the cultivation of the crop. Unfavourable agro-ecological conditions interfere with the production of high quality seed in most Asian potato growing areas, and the availability of high quality seed of the right quantity at the right time remains the most consequential bottleneck to efficient potato production. The seed issue is also the principal problem of potato cultivation in the traditional potato growing areas of Central and Eastern Europe. A review of “the development of integrated systems for large scale propagation of elite plants using in vitro techniques” with specific focus on “potato seed production by tissue culture” is therefore very timely. It provides a platform for analysis and discussion of solutions for some of the most common seed problems facing the potato industry in many parts of the word. All efforts to improve the potato crop and to solve the associated seed problems begin with the right choice and use of the available genetic resources. Resistance to certain pests and diseases has a direct bearing on the success of a seed program. Multiple virus resistance, in particular, would ensure a halt to seed degeneration caused by an accumulation of viruses and thus greatly prolong the ability of seed producers and ware potato growing farmers to grow their crops at great economic benefit. This paper will therefore deal with the current status of the World Potato Collection held in trust by the International Potato Center (CIP) in Peru by presenting up-to-date information on its classification, phytosanitary status and availability of the genetic material and its evaluation data to the breeders worldwide.     

Effect of Thermal Processing on Potato Sensory Profile and off-Odours Detection during Storage

One of the most used thermal treatments in potatoes to inactivate enzymes and prevent their oxidation is the boiling process. This treatment significantly decreases the taste of the potato and causes “off-odours” during storage, whatsoever, represents a big problem for the production of potato-based foodstuffs. This study focused on evaluating the sensory profile of potato slices subjected to a boiling process of three Mexican potato varieties (Alpha, Chica and Gallo) and on off-odours detection in potato produced during storage. According to the examined parameters through PanelCheck, the trained panel had a good performance, resulting 8 of the 12 attributes evaluated were significant. The formation of “cardboard-like off-odour” was detected in the Alpha and Chica varieties at the 24 and 33 h of storage, respectively. Chica potato presented this off-odours with at level significantly lower than Alpha potato (about 30% lower). With respect of Gallo variety, this presented different oxidation olfactory perceptions described by the assessors as “burnt note”, detected after 5 h of refrigerated storage. An adequate election of the variety of potato according to processing will allow an effective utilization of this vegetable and the obtention of potato-based foodstuffs much more stable.     

Potato Crop Nitrogen Status Assessment to Improve N Fertilization Management and Efficiency: Past–Present–Future

Improving nitrogen use efficiency is important for the potato crop, because of its relatively low ability to take up available soil mineral nitrogen (N). Splitting of N fertilizer application is a suitable approach to better match N need and supply. In-season crop N monitoring methods are therefore required to support such strategies. This paper deals with the state of the art and potential development of characteristics, use and implementation of well known and more recent methods aimed to assess in-season potato Crop Nitrogen Status (CNS). A short overview of this concept is given for the potato crop. The most important and available methods for CNS assessment are evaluated for their accuracy, precision, sensitivity, sensibility and feasibility. These are: the petiole sap nitrate concentration test; the leaf chlorophyll concentration measurement using a hand-held chlorophyll meter; the measurement of crop light reflectance through a hand-held radiometer using passive sensors. More recent methods still under investigation based on near, ground-based, air-borne or space-borne remote sensing are discussed for their scientific and practical interest in the near future. The current and potential use and implementation of these methods into decision support systems for potato N fertilization management aimed at improving the potato crop nitrogen use efficiency are analysed by: comparing relative and raw data; establishing threshold values of CNS; and combining or integrating the CNS values into models dedicated to N recommendation or to crop growth simulation.     

GGE Biplots and Traditional Stability Measures for Interpreting Genotype by Environment Interactions

Abstract

Cotton (Gossypium hirsutum L.) breeders conduct multienvironment trials to determine the performance of genotypes in relation to environmental changes and to determine their area of adaptation. The objective of this study was to compare within-model and within-scaling GGE Biplot stability values (GE distance) with those generated by some of the “traditional” stability analytical methods. Correlation coefficients of GE distance of GGE Biplot (stability evaluation) with Cultivar Superiority Measure, Shukla's Stability Variance, Eberhart-Russell regression model, Kang's yield stability statistic, and AMMI were 0.54, 0.91, 0.86, 0.63, and 0.55, respectively. Correlation coefficients between GGE distance of GGE Biplot (mean performance + stability evaluation) and the Cultivar Superiority Measure, the Eberhart-Russell regression model, Kang's yield stability statistic, and AMMI were 0.95, 0.60, 0.85, and ?33, respectively. Some of the “traditional” methods focus heavily on yield, while others focus on stability; GGE Biplot allows for a more versatile and easily comprehensible presentation of the data and variety selection based on both yield and stability. Based on the results of this study and our experience using GGE Biplot, Model 3 (uses replicated and standard error-standardized data) with an entry-focused scaling is the most valuable analysis for breeders to select widely adapted genotypes.     

中国种业科技创新的智能时代——“玉米育种4.0”

二十一世纪是人类社会全面步入人工智能的时代。人工智能与生命科学的结合必将为医疗、健康、农业等行业带来革命性变革,同时也为我国玉米种业的发展提供了千载难逢的历史机遇。回顾育种发展历史,作物育种技术的变迁大致经历了3个阶段,即古近代耕作者基于表型观察开展的农作物驯化与农家品种选育;现代职业育种家借助遗传学与统计学知识,基于经验开展的新品种改良;分子育种工作者应用基因工程和分子标记技术定向改造作物性状。伴随人类社会步入互联网、大数据、人工智能"三位一体"的时代,育种学已步入第4个历史时期。美国科学院院士、玉米遗传育种学家Edwards Buckler教授提出"育种4.0"的理念,未来育种将在基因编辑与合成生物学、基因组与生物信息学、大数据与人工智能等跨学科、多技术支撑下,实现作物新品种的智能、高效、定向培育,最终推动育种学从"艺术"到"科学"到"智能"的革命性转变。